DESCRIPTION: The purpose of the proposed study is to assess the efficacy of a Telephone Linked Communications for Activity Counseling and Tracking (TLC-ACT) program to increase and maintain physical activity levels in older Americans. The TLC-ACT is a computer-based telecommunications system that counsels sedentary individuals to walk regularly and monitors their initiation, adoption and maintenance of regular walking exercise. The TLC-ACT follows the transtheoretical model for behavior change and has been pilot-tested in a randomized study of 68 sedentary older people. The program contacts participants in their homes and asks questions, using a synthesized voice, to determine the user's intention to maintain or change in the pattern of moderate exercise. It encourages intermediate and incremental goals and attempts to overcome individual barriers to exercise. The original system shows considerable promise in pilot tests to improve exercise walking in older Americans, and is based on a successful, similar program to improve hypertension management. The program will be modified and enhanced based on the pilot testing. Modifications will be pretested and subsequently evaluated in a randomized clinical trial of 220 older persons, recruited from six Harvard Community Health Plan Centers. Subjects will be randomized to usual care or special intervention, and will be followed for a six month period with assessments at baseline, two, four, and six months. The principal endpoint is changing physical activity measured by a seven-day recall of physical activity, and by an activity count based on the Caltrac physical activity monitor. Secondary endpoints are based on the behavior model of the physical activity stage of change score. Acceptability of the intervention to the users and primary physicians will be assessed. Cost- effectiveness of intervention will be assessed as well.